1. Field of the Invention
The present invention relates to a magnetic field sensor which can be used for measuring a magnetic field generated by a current flowing through wiring, etc., and also to a system for measuring a magnetic field generated by a current flowing through the wiring, etc.
2. Description of the Related Art
In order to detect EMC (ElectroMagnetic Compatibility) of semiconductor integrated circuits and the like, a high-frequency current which flows to the semiconductor integrated circuits, etc. is measured. This high-frequency current can be measured by measuring a magnetic field which is generated by the current flowing through the semiconductor integrated circuits, etc.
A Hall effect device which utilizes the Hall effect is one of magnetic field sensors which can measure the magnetic field generated from the semiconductor integrated circuits, etc.
In order to measure a magnetic field, a current needs to be supplied to a semiconductor film or a metal film in the Hall effect device. This brings a problem that the Hall effect device consumes high electric power. The Hall effect device requires two input/output terminals for supplying the semiconductor film or the metal film with a current and two input/output terminals for measuring a voltage generated by a magnetic field. Therefore, it is difficult that the Hall effect device is miniaturized.
Another type of a magnetic field sensor, other than the Hall effect device, is one which utilizes electromagnetic induction. Such a magnetic field sensor includes a loop formed of a coaxial cable or conducting wires. The magnetic field sensor can measure the strength of a magnetic filed generated from the semiconductor integrated circuits, etc, by measuring the current which flows to the loop when the strength of the magnetic field varies.
Generally, the magnetic field sensor which utilizes electromagnetic induction is formed of a coaxial cable or conducting wires, etc., thus is large in size compared to the semiconductor integrated circuits. This means that the magnetic field sensor is too large to approach only the wiring from which a magnetic field to be measured is generated. That is, such a magnetic field sensor can not accurately measure the magnetic field which has been generated by a current flowing through a device, wiring, etc.